Thermostat



Jan, 17, 1939. M. PAYNE 2,144,576

THERMOSTAT Filed Oct 23, 1957 2 Sheets-Sheet 1 i ii; "MA

IIFVEIJTOii Kati; Payne deceased, By

bre Parmente Executor by 3% v m'hw.

Attorneys Patented Jan. 17, 1939 UNITED STATES PATENT OFFICE THERMOSTAT Matt Payne, deceased, late of Surbiton, England,

by Fred Parmenter, executor, Kingston-on- Thames, England Application October 23, 1937, Serial No. 170,701 In Great Britain June 8, 1936 1 Claim. (Cl. 29715) This invention relates to thermostats and has that the latter is not affected by the heater, thefor its object to provide improvements in the air drawn into the casing passing over the therconstruction and mounting of thermostats'suitmally sensitive element before it reaches the able for regulating room temperatures and for heating element. like purposes. The invention will now be particularly de- 61 It is convenient and a common practice to scribed with reference to the accompanying mount a thermostat on one of the walls of a drawings in which:- room. It seldom happens, however, that the wall Figure 1 is a sectional view of a thermostat temperature is the same as the room temperaconstructed according to one form of the in- 10 ture. An exterior wall, for example, will be vention, the section being taken on the line A-A l cooler in winter and warmer in summer than the of Figure 2.

interior of the room whilst built-in flues and the Figure 2 is a front elevation of the instrument like may affect the temperature of an internal shown in Fig. 1 and wall. The temperature of the thermostat may Figure 3 is a side elevation of a modified form l therefore differ materially from the general temof instrument fitted with a heater arranged to perature of the room. induce a circulation of air through the cham- One improvement according to the present inber or casing of the thermostat. vention consists in supporting a thermostat from The instrument shown in Figs. 1 and 2 coma wall or like surface in such a way that the prises a main body 8 in the form of a hollow t temperature sensitive element is spaced from the moulding formed with a lateral tubular extenwall or surface and assumes the general temsion 2 having means for attachment to a wall perature of the room rather than the temperaor surface 3 so tha, the main body I is held ture of the wall or surface on which it is mountspaced from the wall and clear of any conveced. In order to protect the sensitive element tion currents induced near the surface or wall.

from thermal currents flowing close to the wall or The top of the body I is covered by a remov- 25 surface, the body of the thermostat containing able cap 6 having openings 5 for the escape of the sensitive element is supported in such a way air from the interior of the body. The tubular that convection currents flowing close to the wall extension 2 is open along the top as indicated or surface can pass between the wall and the at 2a and the cap 4- is provided with an extenbody of the thermostat without flowing over and sion 6 to cover the opening. When the cap is enveloping the body containing the temperature removed the aforesaid opening permits of access sensitive element. to the electrical terminal connections I and 8 A further feature of the invention consists in located in the tubular extension. mounting the sensitive element of a thermostat The thermostatic switch mechanism comprises in a tubular or flue like body or container ara bimetallic strip 9 carried by an elongated sup- 35 ranged to permit of free circulation of air port l0 preferably made of metal and formed at through the body and Over he thermally Sen one end with a hollow threaded part II which is sitive element. When the thermostat is mounted re d into a. socket 52 in the body I as shown, on a wall or surface in the manner described the arrangement being Such that the part '0 40 above, the tubular or flue like body is spaced depends f the body The bimetallic Strip 40 fromfihe Wan Surface so t the Openmgs is fixed at its lower end to the lower end of the therein for the circulation of an are clear of the support In and projects at its upper end through thm sheet hke convectlon stream flows the hollow threaded part II into the interior of over the surface of the wall and wh1ch is heated the b d I Th hon th d d t I I or cooled by the wall surface to a temperature 0 y 6 0w 8 may different from that of the interior of the room. be m the form of hollow cylmder 5pm or Slot A further feature of the invention consists in ted longitudinally at so that after it the provision of a heating device, preferably an has been Screwed into posltlon, it f be a electric resistance heater, arranged to induce a by means a Cfmed end of a p111 Screwed lntO circulation of air through a chamber or casing a lateral opemns m the W of the m y- 50 containing the thermally sensitive element so as This pin may conveniently be the pin 8a carryto promote heat exchange between the thermally ilng thg tgrminal memtbliert8 tas shown in Figure sensitive element and the surrounding air. This of t e rawings so a i serves not only to heating element is arranged in the casing at a lock the elongated support in position, but also point above the temperature sensitive element so to make connection through the support to the 55 bimetallic strip and thence to a moving contact [3 mounted on the free end of the strip.

The contact l3 co-operates with a fixed contact M mounted in the body I and electrically connected to the terminal contact 1.

For the purpose of adjusting the bimetallic strip, a bushing 2| is screwed on to the part H so that the bushing enters into a recess 22 provided for it in the body I. The part of the bushing which projects from this recess is formed with a knurled ring Zia, so that the bushing can be rotated by hand.

The movements of the bushing 2| are imparted to the bimetallic strip through the medium of a push rod IS, the upper end of which is guided in a groove I! formed in the part II and the lower end of which is guided in a hole in a bracket l8 fixed to the bimetallic strip 9 near the fixed end thereof. The rod l6 acts on the bracket is through the medium of a compression spring !5 mounted on the rod l6 and acting between the bracket l8 and a collar I9 fixed to the rod 56. The upper end of the rod [6 carries a disc or plate 2!! which is accommodated in a recess formed in the wall of the part II and which bears against the bushing 2| as shown. When the bushing 2! is rotated so as to cause it to move downwards on the part II, downward movement is imparted to the push rod l6 and thence through the spring I5 to the bracket l8 so that the bimetallic strip is deflected and the working temperature is thus adjusted.

The parts of the support l0, bimetallic strip 9 and rod I6 which project downwards from the body I are enclosed in an open-ended tubular casing 23 screwed to the part II, the upper end of this tubular casing being received within the bushing 2| as shown.

The construction shown in Figs. 1 and 2 of the drawings provides for free circulation of air through the casing 23 and body I for the purpose of facilitating heat exchange between the bimetallic strip and the air in the room or enclosure in which the thermostat is mounted. The body I and casing 23 are so spaced from the wall or surface 3 by means of the tubular extension 2 that the openings in the cover 4 and casing 23 provided for the circulation of air are clear of the thin sheet-like convection stream which flows over the wall or surface 3 and which may be heated or cooled by the surface 3 to 2.

temperature difierent to that of the interior of the room.

The instrument shown in Fig. 3 of the drawings is generally similar to that shown in Figs. 1 and 2 and embodies a thermostat switch comprising a bimetallic strip 9 and adjusting mechanism therefor constructed and adapted to operate in the manner already described with reference to Figs. 1 and 2 of the drawings. In this modified instrument, however, the place of the cover 4 is taken by a cover 24 fitted with a tubular flue like extension 25 in which a heater in the form of an electrical resistance element 46 is mounted. The heater 46 induces a vigorous circulation of air through the casing and thereby promotes heat exchange between the bimetallic strip 9 and the surrounding air.

Since the heating element 46 is located at a point above the bimetallic strip 9, the latter is not materially aifected'by the heater, the air from the interior of the room or enclosure being drawn into the casing 23 through the bottom end thereof and passing over the bimetallic strip 9 before it reaches the heater 46.

It is claimed:

A wall thermostat comprising a flue-like elongated tubular casing having an air inlet at one end and an air outlet at its other end for the circulation of a current of air through said casing, a spacing member attached to said casing at a point remote from the air inlet end thereof for spacing said casing from the wall surface to which the thermostat is attached so that the air inlet end of said casing projects downwardly from the spacing member and a free air space is provided between the downwardly projecting part of the casing and the wall surface to which the thermostat is attached, a bimetallic strip extending longitudinally in and connected at one end to the casing, and a device for adjusting said strip comprising a rod extending longitudinally in the casing and having a yieldable connection at one end to the bimetallic strip in proximity to its connection to the casing, and an annular rotatable adjusting member disposed coaxially of and surrounding the tubular casing and having a threaded connection with the casing to move longitudinally thereof and to act upon said rod to impart longitudinal movement thereto.

' FRED PARMEN'I'ER, Executor of the Estate of Matt Payne, Deceased. 

